Compression braking of an internal combustion engine is a well known concept for enhancing the braking effect of conventional braking systems incorporated in heavy duty trucks, buses and the like. It has been found that the utilization of compression braking significantly reduces wear and stress on the conventional braking system and thus, reduces the incidents of failure of such braking systems. Various compression braking systems have heretofore been utilized; however, because of certain design characteristics, they have been beset with one or more of the following shortcomings: (a) an inordinate number of components are required thereby significantly increasing the complexity and initial cost of the system; (b) the system requires a large and sophisticated hydraulic network; (c) certain of the system components are subjected to severe moment and horizontal reaction forces thereby, resulting in components being bulky and thick in order to withstand such forces; (d) portions of the engine block and head must be redesigned or significantly modified to accommodate the compression braking system; (e) an inordinate amount of space is required to house an engine with a prior compression braking system mounted thereon; (f) the compression braking system is unreliable and requires frequent servicing and adjusting; (g) various components of the system require precise fitting and thus close manufacturing tolerances in order for the system to be in proper working order; and (h) installation of the compression braking system on the engine block or cylinder head is a time-consuming, awkward and difficult operation.